The invention relates generally to manufacturing parts, and more specifically to a method for processing manufactured parts while reducing dimensional errors.
Typically, while manufacturing multiple instances of the same part, the occurrence of variation in the shapes of the parts is expected. The variation typically occurs within predetermined dimensional limits. The limits to variability are desirable to assure that different mating or interrelated parts fit and function correctly with respect to each other.
Dimensional control is also one important factor in determining the cost of a manufactured part. The cost of a part is driven in large part by the size of the allowable variation of the part shape around the desired nominal shape. As the allowable variation becomes smaller, the part becomes more expensive. Such allowable variation of primary features (bending and twisting, for example) can create situations where the addition of secondary features (those referenced from secondary datums located on the bent or twisted shapes) becomes difficult if those secondary features are machined in the nominal locations.
To address such situations created by normal part shape variation, the practice commonly known has “binning” has been developed. Binning is the division of populations of parts into subpopulations of parts related by their ability to be processed by the same process parameters. Typically parts are divided into bins by weight, thickness, or some other readily quantified dimension. Typically, binning addresses simple dimensional variation, but falls short of being able to effectively process multiple sources of shape variation, for instance thickness and twist at the same time.
It is therefore desirable to develop a technique for processing part populations with several sources of shape variation to allow the largest part shape variation while maintaining fit and function and also controlling the cost.